The present invention relates to electrostatic precipitators and, more particularly, to an improved electrostatic precipitator incorporating means for properly positioning the collection electrodes with respect to the discharge electrodes so as to optimally align the electrostatic fields produced within the precipitator.
In the operation of an electrostatic precipitator, a gas laden with entrained particulate material is passed through an electrostatic field established about a discharge electrode disposed between two grounded collector electrodes. The suspended particles become electrically charged as they pass through the electrostatic field and move, under the influence of the electrostatic field, to and deposit upon the grounded collection electrodes flanking the discharge electrode.
Typically, each collecting electrode is formed of one or more elongated plates disposed in a row side by side and suspended from the top of the precipitator housing in a vertical plane. A plurality of such collecting electrodes are disposed transversely across the precipitator casing in spaced vertical planes parallel to the direction of gas flow through the precipitator. A framework of discharge wires is suspended from insulators at the top of the precipitator housing to provide a row of vertical disposed discharge electrode wires between adjacent collecting electrodes across the width of the precipitator.
The positioning of the discharge electrode wires with respect to their adjacent collecting electrode plates is critical. The discharge electrode wire must be exactly equally distant between the collecting electrode plates flanking it in order for the precipitator to operate at maximum efficiency. If any of the discharge electrode wires is closer to one of the collecting electrode plates flanking it than the other, a situation will be presented where there will be a shunning, i.e., a flashover, of voltage between the discharge electrode and the closer of the collecting electrode plates at a voltage lower than the peak operating voltage of the precipitator. Such an occurrence will limit the strength of the field attainable and also lower the operating efficiency of the precipitator.
In the prior art it has been customary to mechanically align the electrostatic fields of the precipitator when the precipitator is out of operation, i.e., in the cold condition. The fields where aligned by visually positioning the discharge electrodes with respect to the collecting electrodes so that the discharge electrodes would be equally distance between the collecting electrode plates. However, some areas of the precipitator were generally inaccessible and proper alignment of these areas could not be assured by the visual method. Additionally, as the discharge electrode wires are supported on a framework suspended on insulators from the top of the precipitator casing, the discharge electrodes are freely moveable at the bottom and under the influence of temperature and gas flow may move out of position during operation. Therefore, properly aligning the discharge electrodes and the collecting electrode plates in the cold condition does not insure that the electrostatic fields will be properly aligned when the precipitator is operating at its normal operating temperature, i.e., the gas temperature, which is typically in the range of 300.degree. to 400.degree. C.
Therefore, it is an object of the present invention to provide an improved electrostatic precipitator wherein alignment of the electrostatic fields is insured at operating temperature.
It is a further object of the present invention to provide means for monitoring the position of the discharge electrode assembly with respect to the collecting plates at operating temperature so as to insure proper alignment of the electrostatic fields.